package com.heima.kafka.sample;

import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.streams.KafkaStreams;
import org.apache.kafka.streams.KeyValue;
import org.apache.kafka.streams.StreamsBuilder;
import org.apache.kafka.streams.StreamsConfig;
import org.apache.kafka.streams.kstream.*;

import java.time.Duration;
import java.util.Arrays;
import java.util.Properties;

public class KafkaStreamQuickStart {
    public static void main(String[] args) {
        Properties prop = new Properties();
        prop.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG,"192.168.200.130:9092");
        prop.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass());
        prop.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG,Serdes.String().getClass());
        prop.put(StreamsConfig.APPLICATION_ID_CONFIG,"stream-quickstart");

        //stream构建器
        StreamsBuilder streamsBuilder = new StreamsBuilder();

        //流式计算
        streamProcessor(streamsBuilder);

        //创建kafkaStream对象
        KafkaStreams kafkaStreams = new KafkaStreams(streamsBuilder.build(),prop);

        //开启流式计算
        kafkaStreams.start();
    }

    /**
     * 流式计算
     * @param streamsBuilder
     */
    private static void streamProcessor(StreamsBuilder streamsBuilder) {
        //创建kstream对象，同时指定从那个topic中接收消息
        KStream<String, String> stream = streamsBuilder.stream("itcast-topic-input");
        /**
         * 处理消息的value
         */
        stream.flatMapValues(value-> {
                //切割消息： hello kafka
                return Arrays.asList(value.split(" "));})
                //按照value进行聚合处理
                .groupBy((( key,value)-> value ))
                //时间窗口
                .windowedBy(TimeWindows.of(Duration.ofSeconds(10)))
                //统计单词的个数
                .count()
                //转换成kstream
                .toStream()
                .map(( key, value) ->{
                        System.out.println("key = " + key);
                        System.out.println("value = " + value);
                        return new KeyValue<>(key.key().toString(),value.toString());
                    })
                //发送消息
                .to("itcast-topic-out");
    }
}
